Department of Renewable Resources, Faculty of Agricultural, Life and Environmental Sciences, University of Alberta, Edmonton, AB, Canada.
Tree Physiol. 2011 Mar;31(3):250-7. doi: 10.1093/treephys/tpr012. Epub 2011 Mar 28.
In a greenhouse study we quantified the gradual change of gas exchange, water relations and root reserves of aspen (Populus tremuloides Michx.) seedlings growing over a 3-month period of severe water stress. The aim of the study was to quantify the complex interrelationship between growth, water and gas exchange, and root carbon (C) dynamics. Various growth, gas exchange and water relations variables in combination with root reserves were measured periodically on seedlings that had been exposed to a continuous drought treatment over a 12-week period and compared with well-watered seedlings. Although gas exchange and water relations parameters significantly decreased over the drought period in aspen seedlings, root reserves did not mirror this trend. During the course of the experiment roots of aspen seedlings growing under severe water stress showed a two orders of magnitude increase in sugar and starch content, and roots of these seedlings contained more starch relative to sugar than those in non-droughted seedlings. Drought resulted in a switch from growth to root reserves storage which indicates a close interrelationship between growth and physiological variables and the accumulation of root carbohydrate reserves. Although a severe 3-month drought period created physiological symptoms of C limitation, there was no indication of a depletion of root C reserve in aspen seedlings.
在一项温室研究中，我们量化了水胁迫严重的 3 个月期间，白杨（Populus tremuloides Michx.）幼苗气体交换、水分关系和根系储备的逐渐变化。本研究的目的是量化生长、水和气体交换以及根系碳（C）动态之间的复杂相互关系。在 12 周的持续干旱处理下，对幼苗进行了定期测量各种生长、气体交换和水分关系变量，并与水分充足的幼苗进行了比较。尽管在干旱期间白杨幼苗的气体交换和水分关系参数显著下降，但根系储备并未反映出这种趋势。在实验过程中，严重缺水条件下生长的白杨幼苗的根中糖和淀粉含量增加了两个数量级，与非干旱条件下的幼苗相比，这些幼苗的根中淀粉相对于糖的含量更高。干旱导致从生长到根系储备储存的转变，这表明生长和生理变量之间存在密切的相互关系，以及根系碳水化合物储备的积累。尽管严重的 3 个月干旱期导致了 C 限制的生理症状，但在白杨幼苗中没有迹象表明根系 C 储备的消耗。
